The present invention is directed generally to photographic equipment and more particularly to the attachment of filters or other accessories to photographic lenses.
Presently, installing or removing a filter from a photographic lens requires the manual and tedious threading and unthreading of the filter from the lens each time a different filter is desired. This task is especially inconvenient during the performance or many photographic assignments, and particularly during weddings, sporting events, or when photographing wildlife. It is also difficult to perform this task with cold or gloved hands, while otherwise distracted, or when the threads of the filter, lens, or both have been damaged.
Hence, the ostensibly routine task of changing a filter often requires a frustrating and inordinate level of concentration to complete. Most photographers are familiar with the recurring difficulty and multiple false starts that attempting to attach filter to lens can entail. As a result, many photographers avoid changing filters unless absolutely necessary, and creative opportunities are thus frequently sacrificed to expediency.
The method of attaching filters to lenses remains perhaps the only feature of photographic equipment design to persist unmodified for several decades. A puzzling oversight, since most photographers appreciate the convenience of, for example, instant bayonet mounts for lens attachment, and quick-release adapters for mounting camera to tripod, both of which eliminate the use of threaded devices.
The standard method for attaching filters to lenses typically features a finely threaded female insert or threaded body along the inside front circumference of a lens barrel. These threads are present to provide a receptive fixture to accept and temporarily hold male-threaded filters or other accessories. Such threads are difficult to machine and prone to cross threading or other damage which renders them burdensome to use or ultimately, unusable. If necessary, re-machining of these threads is expensive and, depending on the value and type of lens, usually impractical. Similarly, photographic filters and other accessories require a correspondingly-threaded male body. Most commonly, filters are machined from aluminum and receive a black anodized finish. Regular installation and removal of the device causes deterioration of the fine anodized threads. This eventually results in the tendency of the filter to bind, particularly when installed into another aluminum fixture, with cross threading damage the usual result. Once damaged, it is not cost-effective to repair a filter, and depending on the extent of damage, may render the filter unusable.
Others have attempted to attach filters or accessories to lenses utilizing magnetic attraction. However all these prior attempts were offered as additive devices to modify or augment existing methods, and none presented a viable alternative to the current industry-standard method. All are characterized by either impractical utility of the design, or unacceptable size and bulk. Some incorporate multiple magnets, specifically polarized and oriented, adding weight and cost, introducing design and manufacturing complexity, and furthermore necessitating specifications to identify polarity and installation orientation of the magnets in order to insure proper functionality of the devices. Consequently, such prior attempts have not met with commercial success.